Asus Taichi 31 is first true ultrabook that sports 2x 13.3 inch IPS panels. As it has 2 screens, it allows the user to use it as tablet when the lid is closed. Thus, there is no need for a rotating hinge. The Taichi 31 features about 7 ours of continuous runtime on a single charge, which pretty amazing for a laptop with 2 screens.
If you cannot live without an optical drive, Asus S550CM might just fit the bill. S550CM features 15.6 inch HD screen that is backed by Nvidia 635M GPU and Core i5 processor.
Asus U38DT is an AMD powered ultrabook powered by AMD A8 4555m processor with integrated Radeon HD 8550M graphics. Despite its low price tag, the U38DT offers backlit keyboard; strong performance; massive hard disk and pre-loaded Windows 8 64 bit operating system. While a high resolution screen would have been nice, Asus seems to have reserved it for the Asus UX31 Zenbook.
Asus Zenbook UX31 is an amazingly gorgeous ultrabook that offers wonderful performance. It is very slim and features an all aluminum design. It has fast wake up time from sleep and has excellent audio. On the downside, the keyboard is not backlit and the display has narrower viewing angles than the Apple Macbook Air ultrabook.